McAleenan was scheduled as the keynote speaker at Georgetown University Law Center during an annual immigration law and policy conference held by the nonprofit immigration think tank Migration Policy Institute. He was expected to take questions from the audience, made up mostly of immigration policy experts, lawyers and advocates.

As he took the stage, a handful of protesters stood up and held large black banners, one read "Hate is Not Normal," and shouted out that children were under attack. They also began yelling the names of children who had died after they were in immigration custody.

Homeland Security is the department that manages immigration enforcement and is largely responsible for meting out many of the massive changes pushed by the Trump administration that has restricting asylum, forced more than 50,000 migrants to wait in Mexico and added hurdles for those seeking green cards. Since December, at least seven children have died after they were taken into immigration custody, and officials have been grappling with a massive influx of migrants that vastly strained the system.

McAleenan, a longtime civil servant who was the head of U.S. Customs and Border Protection before he was tapped to lead DHS, started off saying that he was a longtime law enforcement officer and believed in free speech, but said that public engagement was important.

Some in the audience shouted at the protesters to sit down so they could hear him speak. Doris Meissner, a senior fellow at the Migration Policy Institute who was the head of the agency that preceded Customs and Border protection, was to moderate the Q&A, and told the protesters they were robbing the audience of their ability to engage in a meaningful dialogue on a contentious and important topic.

McAleenan tried to speak at least three times, but eventually left, shaking hands with Meissner and others on stage. Some in the audience cheered when he left.

As Meissner moved on to the next panel, she questioned whether the protesters planned to stay for the whole conference and asked them to take their seats. They obeyed, but many left shortly after.